Magnetic resonance imaging apparatus

Abstract

According to at least one of embodiments, a magnetic resonance imaging apparatus includes an RF coil equipped with a plurality of coil elements and processing circuitry configured to determine a risk of generating artifact caused by mixture of a magnetic resonance signal outside an imaging region of an object, based on imaging conditions and to select at least one coil element used for generating an image of the object from the plurality of coil elements, based on a result of determination of the risk of generating artifact.

What is claimed is: 
     
         1 . A magnetic resonance imaging apparatus comprising:
 an RF coil equipped with a plurality of coil elements; and   processing circuitry configured to
 determine a risk of generating artifact caused by mixture of a magnetic resonance signal outside an imaging region of an object, based on imaging conditions, and 
 select at least one coil element used for generating an image of the object from the plurality of coil elements, based on a result of determination of the risk of generating artifact. 
   
     
     
         2 . The magnetic resonance imaging apparatus according to  claim 1 ,
 wherein the imaging conditions include at least one of slice thickness, an anatomical imaging part, and a type of the RF coil, and   the processing circuitry is configured to determine the risk of generating artifact by using the at least one of the slice thickness, the anatomical imaging part, and the type of the RF coil.   
     
     
         3 . The magnetic resonance imaging apparatus according to  claim 2 ,
 wherein the processing circuitry is configured to determine that there exists the risk of generating the artifact, when the slice thickness is larger than predetermined thickness.   
     
     
         4 . The magnetic resonance imaging apparatus according to  claim 2 ,
 wherein the processing circuitry is configured to determine that there exists the risk of generating the artifact, when width of the anatomical imaging part in a head-foot direction is larger than predetermined width, or when the RF coil belongs to a coil type of imaging an anatomical imaging part whose width in the head-foot direction is larger than the predetermined width.   
     
     
         5 . The magnetic resonance imaging apparatus according to  claim 1 ,
 wherein the plurality of coil elements are divided into a plurality of sections defined in an arrangement unit in a head-foot direction, and   the processing circuitry is configured to sort select at least one of the plurality of coil elements to be used for imaging the object by selecting at least one of the plurality of sections.   
     
     
         6 . The magnetic resonance imaging apparatus according to  claim 1 ,
 wherein the processing circuitry is configured to
 determine whether a magnetic resonance frequency range in the imaging region completely or partially matches with a magnetic resonance frequency range outside the imaging region or not, by using a slope and nonlinearity of a gradient magnetic field corresponding to the imaging conditions, and 
 determine that there exists the risk of generating artifact, when the magnetic resonance frequency range inside the imaging region completely or partially matches with a magnetic resonance frequency range outside the imaging region. 
   
     
     
         7 . The magnetic resonance imaging apparatus according to  claim 6 ,
 wherein the processing circuitry is configured to
 identify a region outside the imaging region whose magnetic resonance frequency range completely or partially matches with the magnetic resonance frequency range inside the imaging region, as a risk region which has a possibility of including a signal source of artifact, 
 determine whether each of the plurality of coil elements covers at least a part of the identified risk region or not, and 
 select each coil element which is determined not to cover any part of the risk region, as coil elements to be used for imaging the object, while deselecting each coil element which is determined to cover at least a part of the risk region. 
   
     
     
         8 . The magnetic resonance imaging apparatus according to  claim 1 ,
 wherein the processing circuitry is configured to
 provisionally select predetermined number of coil elements from the plurality of coil elements based on a position of a magnetic field center, before finally selecting coil elements used for imaging the object, and 
 determine whether the provisional selection is maintained or deselected, based on a result of determination of the risk of generating artifact. 
   
     
     
         9 . The magnetic resonance imaging apparatus according to  claim 7 ,
 wherein the processing circuitry is configured to
 provisionally select predetermined number of coil elements from the plurality of coil elements based on a position of a magnetic field center, before finally selecting coil elements used for imaging the object, and 
 select each coil element which is determined not to cover any part of the risk region while deselecting each coil element covering at least a part of the risk region, out of the predetermined number of coil elements provisionally selected. 
   
     
     
         10 . The magnetic resonance imaging apparatus according to  claim 7 ,
 wherein the processing circuitry is configured to
 further determine whether each coil element determined to cover at least a part of the risk region completely or partially matches with the imaging region or not, and 
 keep selecting each coil element, which is determined to cover at least a part of the risk region and is also determined to completely or partially match with the imaging region, as a coil element used for imaging the object. 
   
     
     
         11 . The magnetic resonance imaging apparatus according to  claim 10 , further comprising a display and a table on which the object is loaded,
 wherein the processing circuitry is configured to cause the display to display at least one of an alarm and a message for prompting movement of the table, when at least one coil element determined to cover at least a part of the risk region is further determined to completely or partially match with the imaging region.